Dan Lewis in Now I know:

What’s going on here? The Slinky comes with a small, barely visible jet pack which allows– no, wait. It’s just physics, even if counterintuitively so.

Let’s start with gravity. Drop something — a ball, your cell phone (which certainly happens all too often), a Slinky, or anything, and gravity will start to pull it down. That’s pretty straightforward. It’s why the top of the Slinky immediately falls once released, and it’s why we expect the rest of the Slinky to fall as well. But that’s not the only force acting on the Slinky. There’s also the tension in the spring.

From the perspective of the Slinky’s bottom, the tension is an upward force. Literally, the tension is pulling the bottom of the Slinky back up toward the top. When you are holding the top end of the Slinky, tension is what keeps it from unraveling entirely and falling to the ground as it stretches and dangles. When you drop it, the spring’s tension doesn’t just disappear, It’s still there and, in this case, pulling up at the same rate that gravity is pulling it downward. So the bottom stays in place as the Slinky compresses.

But in the end, gravity wins. When the top and bottom meet, the tension goes to zero, and the bottom of the Slinky joins the top in its descent back to the ground.

More here. And a bonus video:

Chris Marker (1921-2012), one of France's most influential filmmakers, one of my favorite filmmakers, died yesterday. In memory, we repost a Monday piece by Colin Marshall from a few years ago on Marker's Sans Soleil:

by Colin Marshall

His name is Sandor Krasna, and that's most of the information we have about him. All other qualities of Sans Soleil's verbose, peripatetic protagonist must be inferred from the wrong side of several layers of intermediation. Practically all the footage shown resides on film attributable to Krasna's camera, and practically all the words spoken reside on letters attributable to Krasna's pen. Krasna's shots are linked into a 100-minute collage atop which a nameless female voice, presumably that of Krasna's pen pal, reads the traveling cameraman's meandering, observational missives. The result is one of the most remarkable essay films ever assembled.

The trouble with whipping out the phrase “essay film” is, of course, the need to define the phrase “essay film”. Why not just call Sans Soleil a documentary? The most basic objection is that, well, Sandor Krasna isn't real. He's a fictional character, just like his electronic composer brother Michel Krasna (credited with the score); just like his unidentified female friend, the recipient of so much correspondence. The movie has a whole, if small, cast of players that go unseen, existing only as text, voice, music and an eye through a lens. Marker's choices about how to convey these characters, like many of the choices that make up Sans Soleil, allow — and in fact, force — so much to be generated solely in the viewer's imagination. One might loosely describe the film as a travelogue through time and geography, from mid-1960s Iceland to early-1980s Guinea-Bissau, Cape Verde and Japan, but only because those places are where most of Krasna's footage is shot and provide the raw subject matter for his ruminations. It's up to the mind, conscious or unconscious, of each individual audience member to construct the connective tissue between the shots, the words and the observations. It's not a non-narrative film, exactly; it's simply a film with an emergent narrative, one that differs from mind to mind.